The shooter was identified as Mohammed Saeed Alshamrani, a Saudi Air Force officer who was part of a training mission at the base. Barr said that he was motivated by a "jihadist ideology," but had no ties to any specific terror group.

"This was an act of terrorism," Barr said. "The evidence shows the shooter was influenced by jihadist ideology."

"During the gunfight with the first responders the shooter disengaged long enough to place one of his phones on the floor and shoot a single round into the device," Barr said. "It also appears the other phone was damaged."

He did not say if the government was going to take Apple to court to try to force them to help unlock the phone.

Barr also said investigators found that 21 other Saudi nationals who were in the country for military training, were in possession of "derogatory material." Seventeen of the nationals had jihadist or anti-American content, and at least 15 of them had "some kind of contact with child pornography."

Those individuals have been sent back to Saudi Arabia while the country conducts its own investigation into the allegations. Barr stressed that Saudi Arabia is fully cooperating with U.S. investigators as they probe the deadly attack.

"Further, the kingdom has assured us that if we later decide to charge any of those being sent back to Saudi Arabia in connection with this counterterrorism investigation, they will be returned for trial," Barr said.